Bacterial vaginosis (BV) is a common condition, affecting millions of women annually1, and is associated with numerous health problems including pre-term labor and low birth weight2,3, pelvic inflammatory disease4,5, and acquisition of human immunodeficiency virus6,7. Malodorous vaginal discharge may be the only symptom of BV, and many affected individuals are asymptomatic8.
Studies using cultivation methods have demonstrated that women with BV experience loss of vaginal lactobacilli and concomitant overgrowth of anaerobic and facultative bacteria. Several bacteria have been implicated in BV, such as Gardnerella vaginalis9 and Mobiluncus curtisii10, but these species are also found in subjects without BV, and thus are not specific markers for disease11. For this reason, bacterial cultivation of vaginal fluid has not proven useful for the diagnosis of BV. Rather, clinical criteria or Gram stain analysis of vaginal fluid are employed for diagnosis. At least 3 of 4 elements must be present to fulfill Amsel clinical criteria for BV12, including presence of (1) thin, homogeneous, milky, vaginal discharge; (2) vaginal fluid pH greater than 4.5; (3) positive whiff test—production of fishy odor when 10% potassium hydroxide is added to a slide containing vaginal fluid; and (4) presence of clue cells (>20% of epithelial cells with adherent bacteria) on microscopic examination of vaginal fluid12. An alternative diagnostic approach employs Gram stain of vaginal fluid (Nugent score)13 to distinguish normal vaginal flora (Gram-positive rods, lactobacilli) from BV flora (Gram-negative morphotypes)14.
Koch's postulates for establishing disease causation have not been fulfilled for any bacterium or group of bacteria associated with BV. BV responds to treatment with antibiotics such as metronidazole or clindamycin, but metronidazole has poor in vitro activity against G. vaginalis and M. curtisii. Relapse and persistence are common11. Thus, the etiology and pathogenesis of BV remain poorly understood, and management can be challenging.
Only a fraction of the bacteria present in most microbial ecosystems are amenable to propagation in the laboratory15. Bacteria in complex microbial communities can be identified by characterizing their ribosomal RNA genes (rDNA), an approach that has the advantage of detecting fastidious or cultivation-resistant organisms16. The present invention describes the identification of bacteria present in vaginal fluid samples using an approach employing molecular methods.
The present invention overcomes previous shortcomings in the diagnosis and treatment of bacterial vaginosis by providing compositions and methods of their use in identifying bacteria associated with bacterial vaginosis.